Fixed BasicAnnotationProcessorTest.

Its logic to test that GeneratesCodeProcessor had run before RequiresGeneratedCodeProcessor was incorrect. Specifically:

1. Filer.getResource() does not throw for nonexisting files if the location is the output location.

2. The resource to test should have a ".java" extension.

3. The filer fails if you even try to read a resource that exists.

Instead, we just keep track of whether the GeneratesCodeProcessor has run on elements and check that explicitly.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=92832468

Author: netdpb

common/src/test/java/com/google/auto/common/BasicAnnotationProcessorTest.java

@@ -22,6 +22,7 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.SetMultimap;
+import com.google.common.collect.Sets;
 import com.google.testing.compile.JavaFileObjects;
 
 import org.junit.Test;
@@ -38,15 +39,17 @@
 import javax.lang.model.SourceVersion;
 import javax.lang.model.element.Element;
 import javax.tools.JavaFileObject;
-import javax.tools.StandardLocation;
 
 @RunWith(JUnit4.class)
 public class BasicAnnotationProcessorTest {
+
+  private Set<Element> elementsGeneratingCode = Sets.newHashSet();
+
   @Retention(RetentionPolicy.SOURCE)
   public @interface RequiresGeneratedCode {}
 
   /** Asserts that the code generated by {@link GeneratesCode} and its processor is present.  */
-  public static class RequiresGeneratedCodeProcessor extends BasicAnnotationProcessor {
+  public class RequiresGeneratedCodeProcessor extends BasicAnnotationProcessor {
     boolean processed = false;
 
     @Override
@@ -61,12 +64,7 @@ protected Iterable<? extends ProcessingStep> initSteps() {
         public void process(
             SetMultimap<Class<? extends Annotation>, Element> elementsByAnnotation) {
           processed = true;
-          try {
-            processingEnv.getFiler()
-                .getResource(StandardLocation.SOURCE_OUTPUT, "test", "SomeGeneratedClass");
-          } catch (IOException e) {
-            throw new AssertionError(e);
-          }
+          assertThat(elementsGeneratingCode).isNotEmpty();
         }
 
         @Override
@@ -81,7 +79,8 @@ public Set<? extends Class<? extends Annotation>> annotations() {
   public @interface GeneratesCode {}
 
   /** Generates a class called {@code test.SomeGeneratedClass}. */
-  public static class GeneratesCodeProcessor extends BasicAnnotationProcessor {
+  public class GeneratesCodeProcessor extends BasicAnnotationProcessor {
+
     @Override
     public SourceVersion getSupportedSourceVersion() {
       return SourceVersion.latestSupported();
@@ -109,7 +108,9 @@ public Set<? extends Class<? extends Annotation>> annotations() {
       });
     }
 
+    // TODO(gak): Use jimfs to simulate the file system.
     private void generateClass(Element sourceType) throws IOException {
+      elementsGeneratingCode.add(sourceType);
       JavaFileObject source =
           processingEnv.getFiler().createSourceFile("test.SomeGeneratedClass", sourceType);
       PrintWriter writer = new PrintWriter(source.openWriter());